Rotary mowers have one or more cutter blades mounted to generally vertical shafts, with the cutter blades positioned under a mower deck. Mower decks have been in existence for a number of years, and serve several functions including: (a) protection from rotating cutter blades; (b) protection from thrown clippings and debris; (c) providing an internal surface to promote the flow of air, clippings, and debris in a desired pattern or direction; and (d) mulching of clippings and debris.
Rotary mowers are productive and cost-effective for cutting grass or vegetation, but may generate significant noise. Noise from the mower deck and cutter blades may be caused by turbulent air coming off each blade as it passes through the air under the deck and creates a broadband sound. Additionally, interactions between two or more cutter blades rotating adjacent and in close proximity to each other may result in significant noise, at least in part due to interactions between shapes or irregularities of the blade surfaces.
Noise from the cutter blades may be generated at least in part by the “wing” or “lift” component of the mower blades, a feature which helps lift grass or vegetation off the ground surface. Better lift may result in a better quality of cut and better dispersion of clippings, but also may result in greater noise.
Another source of rotary mower noise may be a fan or blower. Fans or blowers proposed for use on grass mowing equipment may have several different functions. For example, U.S. Pat. Nos. 4,114,353, 5,224,327, 5,542,243, 6,192,666 and 6,675,566 relate to lawn mowers with fans to help blow clippings through a discharge chute into a hopper or grass catcher. U.S. Pat. No. 4,121,405 relates to a rotating disc mounted on a common shaft with a flat rotary cutter blade, the disc having vertical vanes for establishing an air current. U.S. Pat. No. 5,012,633 relates to a lawn mower having a flat cutter blade intended to reduce or minimize wind noise, and also having a discharge fan concentric or nearly concentric with the vertical axis of the cutter blade. U.S. Pat. Nos. 5,873,225 and 5,960,616 relate to rear discharge decks positioned extremely close to the ground, with a radial fan formed integrally with the spindle of the cutting blade and opening near a discharge chute. U.S. Pat. No. 6,073,430 relates to a rotary mower having a fan chamber concentrically positioned over a cutter blade chamber to provide additional suction and to exhaust clippings through an exhaust passage over the deck.
In recent years, there has been a greater need to reduce noise generated by grass mowing equipment. For example, efforts have been made to reduce noise from internal combustion engines that drive mowers and/or cutter blades. Alternative power sources have been substituted in place of internal combustion engines to help reduce the noise level of mowing operations. A mower deck is needed that will produce less noise, without sacrificing quality of cut or dispersion of clippings.
Additionally, there is an increasingly greater need to collect clippings or vegetation from a mower, or to direct discharged material to a desired location with respect to the mower. A mower deck is needed that will provide two or more discharge configurations, without interfering with the power source and linkages that drive the cutting blades.
Mower operators need to be able to view the mower deck, especially when mowing around obstacles and other objects that should be avoided. Better visibility of the mower deck helps the mower operate safely. A mower deck is needed that will produce less noise and/or have multiple discharge configurations, without blocking an operator's view of the mower deck.